Bending and Stretching-Insensitive, Crosstalk-Free, Flexible Pressure Sensor Arrays for Human-Machine Interactions

Accurate data acquisition from flexible sensors placed on deformable 3D freeform surfaces is of critical importance for many applications, such as wearable electronics, human-machine interfaces, and soft robotics. However, the mechanical coupling between the sensor and the deformable subject surface to bending and stretching deformations can significantly reduce the accuracy of the acquired data. This study combines a polyimide (PI) micropore isolation layer (PIL) and serpentine electrodes with a flexible piezoresistive sensor to mitigate the issue of mechanical coupling. As a mechanical buffer to distribute the external pressure and reduce the strain concentration, the PIL can avoid the bending interference for bending curvature up to 256 m⁻¹, while maintaining a high sensitivity of S > 21.5 kPa⁻¹. The serpentine electrode design further allows the sensor to reliably acquire data in the presence of stretching up to 45% without cross-talk. The versatility of the developed sensor is demonstrated in several human-machine interaction scenarios, including gesture recognition and motion detection. The design strategies on materials and structures from this study can also be applied for the development of other flexible sensors with high sensitivity and low deformation interference to avoid the mechanical coupling between the sensor and the deformable surface.